Please provide the 14.8 config.ini, 14.12 config.ini, make sure that the .csv files are actually the opaque format files saved by the save() command on the 14.8 system (and not some csv format files left behind by an earlier load process).
The error suggests that the data has collisions, i.e. cells/chunks with the same coordinates.
If you look at scidb.log on instance 20, you should see something like
…[WARN] … Data collision … at pos XXX
XXX is the cell/chunk coordinate which scidb thinks is duplicated.
Executing
/opt/scidb/14.12/bin/iquery -an -q load(current_speed,‘current_speed_backup3.csv’,-1,‘opaque’,0,true)
will make load() detect data collisions and should force it to error out with the same information as in the log file on instance 20.

Before we can figure out how to recover, we need to diagnose the problem. If you dont mind, please provide us with the config.ini (14.8 & 14.12) and the scidb.log files preferably from all the instances. One way of getting most of that information is by running ‘scidb.py dbginfo[-lt] …’ And please make sure the .csv files that you are trying to load as the saved opaque backup files are in fact what they are on all the instances.